\( \displaystyle \sum_{k=0}^{6} {}^{\,51-k}\!C_{3} \) is equal to:
\( {}^{52}\!C_{3}-{}^{45}\!C_{3} \)
\( {}^{51}\!C_{4}-{}^{45}\!C_{4} \)
\( {}^{51}\!C_{3}-{}^{45}\!C_{3} \)
\( {}^{52}\!C_{4}-{}^{45}\!C_{4} \)