If gcd(a,c)=1\gcd(a, c) = 1gcd(a,c)=1 and gcd(b,c)=1\gcd(b, c) = 1gcd(b,c)=1, which of the following must be true?
gcd(a,b)=1\gcd(a, b) = 1gcd(a,b)=1
gcd(a+b,c)=1\gcd(a+b, c) = 1gcd(a+b,c)=1
gcd(ab,c)=1\gcd(ab, c) = 1gcd(ab,c)=1
gcd(a⋅b⋅c,a+b+c)=1\gcd(a \cdot b \cdot c, a+b+c) = 1gcd(a⋅b⋅c,a+b+c)=1