Which low level language should I study for penetration testing; C, C#, C++?

I'll note that I already know some Python and have coded some basic tools: crawler, xss/sqli scanner, mac changer, arp spoofer and more.

Also, what exactly can I do with C family that I can't with Python? I see it's recommended and desired in job postings, but I'm not sure why.

cybersecurity language penetration penetration testing study testing