<｜begin▁of▁sentence｜>### Instruction:
Imagine you are assessing the migratory patterns of a certain species of fish in a network of interconnected underwater channels. Each channel between two locations has a varying current strength, which effectively represents the 'cost' or 'energy expenditure' for the fish to travel through. You've mapped these channels as pathways with their respective current strengths: A to B has a current strength of 4, B to C is 2, A to C is 5, and C to D is 1.

Your task is to analyze the movements starting from the breeding ground located at point A to all the other points in the network, finding the routes that would minimize the energy expenditure for the fish. To accomplish this using the data you've gathered, apply NetworkX's single_source_dijkstra function to compute the most energy-efficient paths and their associated costs from A to all other points in the underwater network.

Additionally, you are particularly interested in the pathway from the breeding ground A to the feeding area D. Identify the route that the fish would most likely take to get to D using the least amount of energy and determine the exact energy cost for this journey. 

(Please note that the data provided above should be integrated into your analysis, but the actual computation or step-by-step guidance is not required in this scenario—only the rephrased question is needed.)
### Response:
import networkx as nx

# Create a weighted graph
G = nx.Graph()
G.add_edge('A', 'B', weight=4)
G.add_edge('B', 'C', weight=2)
G.add_edge('A', 'C', weight=5)
G.add_edge('C', 'D', weight=1)

# Compute the shortest path and its length from source A to all other nodes
length, path = nx.single_source_dijkstra(G, source='A')

# Output the results
for target_node in path:
    print(f'Shortest path from A to {target_node}: {path[target_node]} with length {length[target_node]}')

# Specific target
length_to_target, path_to_target = nx.single_source_dijkstra(G, source='A', target='D')
print(f'Shortest path from A to D: {path_to_target} with length {length_to_target}')
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