Quark Composition in Nuclei Steps:

• Protons consist of 2 up quarks and 1 down quark; neutrons consist of 1 up quark and 2 down quarks.
• For a nucleus with atomic number Z (protons) and neutron number N, total up quarks = 2Z + N; total down quarks = Z + 2N.
• Identify the nucleus as chlorine-37 (Z = 17, A = 37, so N = 20).
• Calculate: up quarks = 2(17) + 20 = 54; down quarks = 17 + 2(20) = 57.

Why B is correct:

• Matches the formula for up and down quarks in a chlorine-37 nucleus (Z=17, N=20).

Why the others are wrong:

• A implies Z=14, N=23 (inconsistent with chlorine-37).
• C implies Z=19, N=15 (inconsistent with chlorine-37).
• D implies Z=20, N=11 (inconsistent with chlorine-37).

Final answer: B