$4-$ What causes the signal multiplicities in spin$-$coupled $13$C$-$NMR spectra?

A$){?}^{13}C-{?}^{13}C$ spin$-$spin coupling

B$){?}^{13}C-{?}^{12}C$ spin$-$spin coupling

C$){?}^{13}C-{?}^{-1}H$ spin$-$spin coupling

D$){?}^{1}H-{?}^{1}H$ spin$-$spin coupling

$5-$ The relative peak intensities of multiplets can be described with the "Pascal triangle:" Using the Pascal triangle, what is the correct ratio of the intensities of a quartet?

A$)1$:$1$:$1$:$1$

$)1$:$2$:$2$:$1$

C$)1$:$3$:$3$:$1$

D$)1$:$4$:$4$:$1$

$6-$ Which of the following characterizes the unusually intense peak of alkyl chlorides in MS spectrometry?

A$)M+1$ peak

B$)M+2$ peak

C$)$ base peak

D$)$ parent peak