Which of the following reagents can be used to oxidised primary alcohol to aldehydes ?

Question

$\begin{array}{1 1} \text{CrO_3 in anhydrous medium } \\ KMnO_4 \text {in acidic medium } \\ \text{pyridinium chlorochromate} \\ \text{Heat in the presence of Cu at 573 k} \end{array}$