@Q1: We are fine with the removal of the reference in the abstract.

@Q2: The acronym APD represents the word "Avalanche Photodetector" and is not used to represent a mathematical symbol anywhere in the text. The definition of the acronym precedes its first usage, and "APD" is commonly used in the community to refer to this type of device detecting single photons. We therefore believe the reference to the policy of not using multi-letter symbols to represent mathematical elements does not apply. Perhaps confusion arose from us using subscript indices to distinguish the different devices, but we think the experiment is easier to understand when we explain which detector is used for what in the main text. We suggest to leave the acronym as-is.

Q3: We checked with a senior author of this paper - it is still in first review, so there is no updated reference.

FQ: The funding agency's full chosen reference is "National Research Foundation, Prime Minister’s office" [of Singapore] as indicated in the text, but likely there are several similar entries in databases. What we refer to is the entity that corresponds to http://dx.doi.org/10.13039/501100001381

We went through the rest of the proofs, and carried out the requested link checks and confirm they are correct.

Thanks for the careful editing and Merry Christmas :)