C-12-Q050mediumsingle_mcqFor a non-zero vector a⃗\vec{a}a, 1∣a⃗∣a⃗\frac{1}{|\vec{a}|}\vec{a}∣a∣1a isaZero vectorbA unit vector along a⃗\vec{a}aca⃗\vec{a}a itselfdNegative of a⃗\vec{a}a